//===-- llvm/MC/WinCOFFObjectWriter.cpp -------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains an implementation of a Win32 COFF object file writer.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "WinCOFFObjectWriter"

#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCValue.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCSectionCOFF.h"

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"

#include "llvm/Support/COFF.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"

#include "llvm/Support/TimeValue.h"

//#include "../Target/X86/MCTargetDesc/X86FixupKinds.h"
//===-- X86/X86FixupKinds.h - X86 Specific Fixup Entries --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_X86_X86FIXUPKINDS_H
#define LLVM_X86_X86FIXUPKINDS_H

#include "llvm/MC/MCFixup.h"

namespace llvm {
	namespace X86 {
		enum Fixups {
			reloc_riprel_4byte = FirstTargetFixupKind, // 32-bit rip-relative
			reloc_riprel_4byte_movq_load,              // 32-bit rip-relative in movq
			reloc_signed_4byte,                        // 32-bit signed. Unlike FK_Data_4
			// this will be sign extended at
			// runtime.
			reloc_global_offset_table,                 // 32-bit, relative to the start
			// of the instruction. Used only
			// for _GLOBAL_OFFSET_TABLE_.
			// Marker
			LastTargetFixupKind,
			NumTargetFixupKinds = LastTargetFixupKind - FirstTargetFixupKind
		};
	}
}

#endif

#include <cstdio>

using namespace llvm;

namespace {
	typedef llvm::SmallString<COFF::NameSize> name;

	enum AuxiliaryType {
		ATFunctionDefinition,
		ATbfAndefSymbol,
		ATWeakExternal,
		ATFile,
		ATSectionDefinition
	};

	struct AuxSymbol {
		AuxiliaryType   AuxType;
		COFF::Auxiliary Aux;
	};

	class COFFSymbol;
	class COFFSection;

	class COFFSymbol {
	public:
		COFF::symbol Data;

		typedef llvm::SmallVector<AuxSymbol, 1> AuxiliarySymbols;

		name             Name;
		int              Index;
		AuxiliarySymbols Aux;
		COFFSymbol      *Other;
		COFFSection     *Section;
		int              Relocations;

		MCSymbolData const *MCData;

		COFFSymbol(llvm::StringRef name);
		size_t size() const;
		void set_name_offset(uint32_t Offset);

		bool should_keep() const;
	};

	// This class contains staging data for a COFF relocation entry.
	struct COFFRelocation {
		COFF::relocation Data;
		COFFSymbol          *Symb;

		COFFRelocation() : Symb(NULL) {}
		static size_t size() { return COFF::RelocationSize; }
	};

	typedef std::vector<COFFRelocation> relocations;

	class COFFSection {
	public:
		COFF::section Header;

		std::string          Name;
		int                  Number;
		MCSectionData const *MCData;
		COFFSymbol          *Symbol;
		relocations          Relocations;

		COFFSection(llvm::StringRef name);
		static size_t size();
	};

	// This class holds the COFF string table.
	class StringTable {
		typedef llvm::StringMap<size_t> map;
		map Map;

		void update_length();
	public:
		std::vector<char> Data;

		StringTable();
		size_t size() const;
		size_t insert(llvm::StringRef String);
	};

	class WinCOFFObjectWriter : public MCObjectWriter {
	public:

		typedef std::vector<COFFSymbol*>  symbols;
		typedef std::vector<COFFSection*> sections;

		typedef DenseMap<MCSymbol  const *, COFFSymbol *>   symbol_map;
		typedef DenseMap<MCSection const *, COFFSection *> section_map;

		// Root level file contents.
		bool Is64Bit;
		COFF::header Header;
		sections     Sections;
		symbols      Symbols;
		StringTable  Strings;

		// Maps used during object file creation.
		section_map SectionMap;
		symbol_map  SymbolMap;

		WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit);
		~WinCOFFObjectWriter();

		COFFSymbol *createSymbol(StringRef Name);
		COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
		COFFSection *createSection(StringRef Name);

		template <typename object_t, typename list_t>
		object_t *createCOFFEntity(llvm::StringRef Name, list_t &List);

		void DefineSection(MCSectionData const &SectionData);
		void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler);

		void MakeSymbolReal(COFFSymbol &S, size_t Index);
		void MakeSectionReal(COFFSection &S, size_t Number);

		bool ExportSection(COFFSection const *S);
		bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);

		bool IsPhysicalSection(COFFSection *S);

		// Entity writing methods.

		void WriteFileHeader(const COFF::header &Header);
		void WriteSymbol(const COFFSymbol *S);
		void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
		void WriteSectionHeader(const COFF::section &S);
		void WriteRelocation(const COFF::relocation &R);

		// MCObjectWriter interface implementation.

		void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);

		void RecordRelocation(const MCAssembler &Asm,
			const MCAsmLayout &Layout,
			const MCFragment *Fragment,
			const MCFixup &Fixup,
			MCValue Target,
			uint64_t &FixedValue);

		void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
	};
}

static inline void write_uint32_le(void *Data, uint32_t const &Value) {
	uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
	Ptr[0] = (Value & 0x000000FF) >>  0;
	Ptr[1] = (Value & 0x0000FF00) >>  8;
	Ptr[2] = (Value & 0x00FF0000) >> 16;
	Ptr[3] = (Value & 0xFF000000) >> 24;
}

static inline void write_uint16_le(void *Data, uint16_t const &Value) {
	uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
	Ptr[0] = (Value & 0x00FF) >> 0;
	Ptr[1] = (Value & 0xFF00) >> 8;
}

static inline void write_uint8_le(void *Data, uint8_t const &Value) {
	uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
	Ptr[0] = (Value & 0xFF) >> 0;
}

//------------------------------------------------------------------------------
// Symbol class implementation

COFFSymbol::COFFSymbol(llvm::StringRef name)
	: Name(name.begin(), name.end())
	, Other(NULL)
	, Section(NULL)
	, Relocations(0)
	, MCData(NULL) {
		memset(&Data, 0, sizeof(Data));
}

size_t COFFSymbol::size() const {
	return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
}

// In the case that the name does not fit within 8 bytes, the offset
// into the string table is stored in the last 4 bytes instead, leaving
// the first 4 bytes as 0.
void COFFSymbol::set_name_offset(uint32_t Offset) {
	write_uint32_le(Data.Name + 0, 0);
	write_uint32_le(Data.Name + 4, Offset);
}

/// logic to decide if the symbol should be reported in the symbol table
bool COFFSymbol::should_keep() const {
	// no section means its external, keep it
	if (Section == NULL)
		return true;

	// if it has relocations pointing at it, keep it
	if (Relocations > 0)   {
		assert(Section->Number != -1 && "Sections with relocations must be real!");
		return true;
	}

	// if the section its in is being droped, drop it
	if (Section->Number == -1)
		return false;

	// if it is the section symbol, keep it
	if (Section->Symbol == this)
		return true;

	// if its temporary, drop it
	if (MCData && MCData->getSymbol().isTemporary())
		return false;

	// otherwise, keep it
	return true;
}

//------------------------------------------------------------------------------
// Section class implementation

COFFSection::COFFSection(llvm::StringRef name)
	: Name(name)
	, MCData(NULL)
	, Symbol(NULL) {
		memset(&Header, 0, sizeof(Header));
}

size_t COFFSection::size() {
	return COFF::SectionSize;
}

//------------------------------------------------------------------------------
// StringTable class implementation

/// Write the length of the string table into Data.
/// The length of the string table includes uint32 length header.
void StringTable::update_length() {
	write_uint32_le(&Data.front(), Data.size());
}

StringTable::StringTable() {
	// The string table data begins with the length of the entire string table
	// including the length header. Allocate space for this header.
	Data.resize(4);
}

size_t StringTable::size() const {
	return Data.size();
}

/// Add String to the table iff it is not already there.
/// @returns the index into the string table where the string is now located.
size_t StringTable::insert(llvm::StringRef String) {
	map::iterator i = Map.find(String);

	if (i != Map.end())
		return i->second;

	size_t Offset = Data.size();

	// Insert string data into string table.
	Data.insert(Data.end(), String.begin(), String.end());
	Data.push_back('\0');

	// Put a reference to it in the map.
	Map[String] = Offset;

	// Update the internal length field.
	update_length();

	return Offset;
}

//------------------------------------------------------------------------------
// WinCOFFObjectWriter class implementation

WinCOFFObjectWriter::WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit)
	: MCObjectWriter(OS, true)
	, Is64Bit(is64Bit) {
		memset(&Header, 0, sizeof(Header));

		Is64Bit ? Header.Machine = COFF::IMAGE_FILE_MACHINE_AMD64
			: Header.Machine = COFF::IMAGE_FILE_MACHINE_I386;
}

WinCOFFObjectWriter::~WinCOFFObjectWriter() {
	for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
		delete *I;
	for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
		delete *I;
}

COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
	return createCOFFEntity<COFFSymbol>(Name, Symbols);
}

COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
	symbol_map::iterator i = SymbolMap.find(Symbol);
	if (i != SymbolMap.end())
		return i->second;
	COFFSymbol *RetSymbol
		= createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
	SymbolMap[Symbol] = RetSymbol;
	return RetSymbol;
}

COFFSection *WinCOFFObjectWriter::createSection(llvm::StringRef Name) {
	return createCOFFEntity<COFFSection>(Name, Sections);
}

/// A template used to lookup or create a symbol/section, and initialize it if
/// needed.
template <typename object_t, typename list_t>
object_t *WinCOFFObjectWriter::createCOFFEntity(llvm::StringRef Name,
	list_t &List) {
		object_t *Object = new object_t(Name);

		List.push_back(Object);

		return Object;
}

/// This function takes a section data object from the assembler
/// and creates the associated COFF section staging object.
void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
	assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
		&& "Got non COFF section in the COFF backend!");
	// FIXME: Not sure how to verify this (at least in a debug build).
	MCSectionCOFF const &Sec =
		static_cast<MCSectionCOFF const &>(SectionData.getSection());

	COFFSection *coff_section = createSection(Sec.getSectionName());
	COFFSymbol  *coff_symbol = createSymbol(Sec.getSectionName());

	coff_section->Symbol = coff_symbol;
	coff_symbol->Section = coff_section;
	coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;

	// In this case the auxiliary symbol is a Section Definition.
	coff_symbol->Aux.resize(1);
	memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
	coff_symbol->Aux[0].AuxType = ATSectionDefinition;
	coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();

	coff_section->Header.Characteristics = Sec.getCharacteristics();

	uint32_t &Characteristics = coff_section->Header.Characteristics;
	switch (SectionData.getAlignment()) {
	case 1:    Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES;    break;
	case 2:    Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES;    break;
	case 4:    Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES;    break;
	case 8:    Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES;    break;
	case 16:   Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES;   break;
	case 32:   Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES;   break;
	case 64:   Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES;   break;
	case 128:  Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES;  break;
	case 256:  Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES;  break;
	case 512:  Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES;  break;
	case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
	case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
	case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
	case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
	default:
		llvm_unreachable("unsupported section alignment");
	}

	// Bind internal COFF section to MC section.
	coff_section->MCData = &SectionData;
	SectionMap[&SectionData.getSection()] = coff_section;
}

/// This function takes a section data object from the assembler
/// and creates the associated COFF symbol staging object.
void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
	MCAssembler &Assembler) {
		COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&SymbolData.getSymbol());

		coff_symbol->Data.Type         = (SymbolData.getFlags() & 0x0000FFFF) >>  0;
		coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;

		if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
			coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;

			if (SymbolData.getSymbol().isVariable()) {
				coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
				const MCExpr *Value = SymbolData.getSymbol().getVariableValue();

				// FIXME: This assert message isn't very good.
				assert(Value->getKind() == MCExpr::SymbolRef &&
					"Value must be a SymbolRef!");

				const MCSymbolRefExpr *SymbolRef =
					static_cast<const MCSymbolRefExpr *>(Value);
				coff_symbol->Other = GetOrCreateCOFFSymbol(&SymbolRef->getSymbol());
			} else {
				std::string WeakName = std::string(".weak.")
					+  SymbolData.getSymbol().getName().str()
					+ ".default";
				COFFSymbol *WeakDefault = createSymbol(WeakName);
				WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
				WeakDefault->Data.StorageClass  = COFF::IMAGE_SYM_CLASS_EXTERNAL;
				WeakDefault->Data.Type          = 0;
				WeakDefault->Data.Value         = 0;
				coff_symbol->Other = WeakDefault;
			}

			// Setup the Weak External auxiliary symbol.
			coff_symbol->Aux.resize(1);
			memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
			coff_symbol->Aux[0].AuxType = ATWeakExternal;
			coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
			coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
				COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
		}

		// If no storage class was specified in the streamer, define it here.
		if (coff_symbol->Data.StorageClass == 0) {
			bool external = SymbolData.isExternal() || (SymbolData.Fragment == NULL);

			coff_symbol->Data.StorageClass =
				external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
		}

		if (SymbolData.Fragment != NULL)
			coff_symbol->Section =
			SectionMap[&SymbolData.Fragment->getParent()->getSection()];

		// Bind internal COFF symbol to MC symbol.
		coff_symbol->MCData = &SymbolData;
		SymbolMap[&SymbolData.getSymbol()] = coff_symbol;
}

/// making a section real involves assigned it a number and putting
/// name into the string table if needed
void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
	if (S.Name.size() > COFF::NameSize) {
		size_t StringTableEntry = Strings.insert(S.Name.c_str());

		// FIXME: Why is this number 999999? This number is never mentioned in the
		// spec. I'm assuming this is due to the printed value needing to fit into
		// the S.Header.Name field. In which case why not 9999999 (7 9's instead of
		// 6)? The spec does not state if this entry should be null terminated in
		// this case, and thus this seems to be the best way to do it. I think I
		// just solved my own FIXME...
		if (StringTableEntry > 999999)
			report_fatal_error("COFF string table is greater than 999999 bytes.");

		std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
	} else
		std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());

	S.Number = Number;
	S.Symbol->Data.SectionNumber = S.Number;
	S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
}

void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
	if (S.Name.size() > COFF::NameSize) {
		size_t StringTableEntry = Strings.insert(S.Name.c_str());

		S.set_name_offset(StringTableEntry);
	} else
		std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
	S.Index = Index;
}

bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) {
	return !S->MCData->getFragmentList().empty();
}

bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
	MCAssembler &Asm) {
		// This doesn't seem to be right. Strings referred to from the .data section
		// need symbols so they can be linked to code in the .text section right?

		// return Asm.isSymbolLinkerVisible (&SymbolData);

		// For now, all non-variable symbols are exported,
		// the linker will sort the rest out for us.
		return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
}

bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
	return (S->Header.Characteristics
		& COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
}

//------------------------------------------------------------------------------
// entity writing methods

void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
	WriteLE16(Header.Machine);
	WriteLE16(Header.NumberOfSections);
	WriteLE32(Header.TimeDateStamp);
	WriteLE32(Header.PointerToSymbolTable);
	WriteLE32(Header.NumberOfSymbols);
	WriteLE16(Header.SizeOfOptionalHeader);
	WriteLE16(Header.Characteristics);
}

void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
	WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
	WriteLE32(S->Data.Value);
	WriteLE16(S->Data.SectionNumber);
	WriteLE16(S->Data.Type);
	Write8(S->Data.StorageClass);
	Write8(S->Data.NumberOfAuxSymbols);
	WriteAuxiliarySymbols(S->Aux);
}

void WinCOFFObjectWriter::WriteAuxiliarySymbols(
	const COFFSymbol::AuxiliarySymbols &S) {
		for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
			i != e; ++i) {
				switch(i->AuxType) {
				case ATFunctionDefinition:
					WriteLE32(i->Aux.FunctionDefinition.TagIndex);
					WriteLE32(i->Aux.FunctionDefinition.TotalSize);
					WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
					WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
					WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
					break;
				case ATbfAndefSymbol:
					WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
					WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
					WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
					WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
					WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
					break;
				case ATWeakExternal:
					WriteLE32(i->Aux.WeakExternal.TagIndex);
					WriteLE32(i->Aux.WeakExternal.Characteristics);
					WriteZeros(sizeof(i->Aux.WeakExternal.unused));
					break;
				case ATFile:
					WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
						sizeof(i->Aux.File.FileName)));
					break;
				case ATSectionDefinition:
					WriteLE32(i->Aux.SectionDefinition.Length);
					WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
					WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
					WriteLE32(i->Aux.SectionDefinition.CheckSum);
					WriteLE16(i->Aux.SectionDefinition.Number);
					Write8(i->Aux.SectionDefinition.Selection);
					WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
					break;
				}
		}
}

void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
	WriteBytes(StringRef(S.Name, COFF::NameSize));

	WriteLE32(S.VirtualSize);
	WriteLE32(S.VirtualAddress);
	WriteLE32(S.SizeOfRawData);
	WriteLE32(S.PointerToRawData);
	WriteLE32(S.PointerToRelocations);
	WriteLE32(S.PointerToLineNumbers);
	WriteLE16(S.NumberOfRelocations);
	WriteLE16(S.NumberOfLineNumbers);
	WriteLE32(S.Characteristics);
}

void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
	WriteLE32(R.VirtualAddress);
	WriteLE32(R.SymbolTableIndex);
	WriteLE16(R.Type);
}

////////////////////////////////////////////////////////////////////////////////
// MCObjectWriter interface implementations

void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
	const MCAsmLayout &Layout) {
		// "Define" each section & symbol. This creates section & symbol
		// entries in the staging area.

		for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
			DefineSection(*i);

		for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
			e = Asm.symbol_end(); i != e; i++) {
				if (ExportSymbol(*i, Asm))
					DefineSymbol(*i, Asm);
		}
}

void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
	const MCAsmLayout &Layout,
	const MCFragment *Fragment,
	const MCFixup &Fixup,
	MCValue Target,
	uint64_t &FixedValue) {
		assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");

		const MCSymbol *A = &Target.getSymA()->getSymbol();
		MCSymbolData &A_SD = Asm.getSymbolData(*A);

		MCSectionData const *SectionData = Fragment->getParent();

		// Mark this symbol as requiring an entry in the symbol table.
		assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
			"Section must already have been defined in ExecutePostLayoutBinding!");
		assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
			"Symbol must already have been defined in ExecutePostLayoutBinding!");

		COFFSection *coff_section = SectionMap[&SectionData->getSection()];
		COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
		const MCSymbolRefExpr *SymA = Target.getSymA();
		const MCSymbolRefExpr *SymB = Target.getSymB();
		const bool CrossSection = SymB &&
			&SymA->getSymbol().getSection() != &SymB->getSymbol().getSection();

		if (Target.getSymB()) {
			const MCSymbol *B = &Target.getSymB()->getSymbol();
			MCSymbolData &B_SD = Asm.getSymbolData(*B);

			// Offset of the symbol in the section
			int64_t a = Layout.getSymbolOffset(&B_SD);

			// Ofeset of the relocation in the section
			int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();

			FixedValue = b - a;
			// In the case where we have SymbA and SymB, we just need to store the delta
			// between the two symbols.  Update FixedValue to account for the delta, and
			// skip recording the relocation.
			if (!CrossSection)
				return;
		} else {
			FixedValue = Target.getConstant();
		}

		COFFRelocation Reloc;

		Reloc.Data.SymbolTableIndex = 0;
		Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);

		// Turn relocations for temporary symbols into section relocations.
		if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
			Reloc.Symb = coff_symbol->Section->Symbol;
			FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
				+ coff_symbol->MCData->getOffset();
		} else
			Reloc.Symb = coff_symbol;

		++Reloc.Symb->Relocations;

		Reloc.Data.VirtualAddress += Fixup.getOffset();

		unsigned FixupKind = Fixup.getKind();

		if (CrossSection)
			FixupKind = FK_PCRel_4;

		switch (FixupKind) {
		case FK_PCRel_4:
		case X86::reloc_riprel_4byte:
		case X86::reloc_riprel_4byte_movq_load:
			Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_REL32
				: COFF::IMAGE_REL_I386_REL32;
			// FIXME: Can anyone explain what this does other than adjust for the size
			// of the offset?
			FixedValue += 4;
			break;
		case FK_Data_4:
		case X86::reloc_signed_4byte:
			Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32
				: COFF::IMAGE_REL_I386_DIR32;
			break;
		case FK_Data_8:
			if (Is64Bit)
				Reloc.Data.Type = COFF::IMAGE_REL_AMD64_ADDR64;
			else
				llvm_unreachable("unsupported relocation type");
			break;
		default:
			llvm_unreachable("unsupported relocation type");
		}

		coff_section->Relocations.push_back(Reloc);
}

void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
	const MCAsmLayout &Layout) {
		// Assign symbol and section indexes and offsets.
		Header.NumberOfSections = 0;

		for (sections::iterator i = Sections.begin(),
			e = Sections.end(); i != e; i++) {
				if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
					MakeSectionReal(**i, ++Header.NumberOfSections);
				} else {
					(*i)->Number = -1;
				}
		}

		Header.NumberOfSymbols = 0;

		for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
			COFFSymbol *coff_symbol = *i;
			MCSymbolData const *SymbolData = coff_symbol->MCData;

			// Update section number & offset for symbols that have them.
			if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
				assert(coff_symbol->Section != NULL);

				coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
				coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
					+ SymbolData->Offset;
			}

			if (coff_symbol->should_keep()) {
				MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);

				// Update auxiliary symbol info.
				coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
				Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
			} else
				coff_symbol->Index = -1;
		}

		// Fixup weak external references.
		for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
			COFFSymbol *coff_symbol = *i;
			if (coff_symbol->Other != NULL) {
				assert(coff_symbol->Index != -1);
				assert(coff_symbol->Aux.size() == 1 &&
					"Symbol must contain one aux symbol!");
				assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
					"Symbol's aux symbol must be a Weak External!");
				coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
			}
		}

		// Assign file offsets to COFF object file structures.

		unsigned offset = 0;

		offset += COFF::HeaderSize;
		offset += COFF::SectionSize * Header.NumberOfSections;

		for (MCAssembler::const_iterator i = Asm.begin(),
			e = Asm.end();
			i != e; i++) {
				COFFSection *Sec = SectionMap[&i->getSection()];

				if (Sec->Number == -1)
					continue;

				Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);

				if (IsPhysicalSection(Sec)) {
					Sec->Header.PointerToRawData = offset;

					offset += Sec->Header.SizeOfRawData;
				}

				if (Sec->Relocations.size() > 0) {
					//printf("Sec->Relocations.size() is %d\n",(int)Sec->Relocations.size());
					//Sec->Header.NumberOfRelocations = Sec->Relocations.size();
					Sec->Header.NumberOfRelocations = -1;
					Sec->Header.PointerToRelocations = offset;

					offset += COFF::RelocationSize * (Sec->Relocations.size()+1);

					for (relocations::iterator cr = Sec->Relocations.begin(),
						er = Sec->Relocations.end();
						cr != er; ++cr) {
							assert((*cr).Symb->Index != -1);
							(*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
					}
				}

				assert(Sec->Symbol->Aux.size() == 1
					&& "Section's symbol must have one aux!");
				AuxSymbol &Aux = Sec->Symbol->Aux[0];
				assert(Aux.AuxType == ATSectionDefinition &&
					"Section's symbol's aux symbol must be a Section Definition!");
				Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
				Aux.Aux.SectionDefinition.NumberOfRelocations =
					Sec->Header.NumberOfRelocations;
				Aux.Aux.SectionDefinition.NumberOfLinenumbers =
					Sec->Header.NumberOfLineNumbers;
		}

		Header.PointerToSymbolTable = offset;

		Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();

		// Write it all to disk...
		WriteFileHeader(Header);

		{
			sections::iterator i, ie;
			MCAssembler::const_iterator j, je;

			for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
				if ((*i)->Number != -1)
					WriteSectionHeader((*i)->Header);

			for (i = Sections.begin(), ie = Sections.end(),
				j = Asm.begin(), je = Asm.end();
				(i != ie) && (j != je); ++i, ++j) {

					if ((*i)->Number == -1)
						continue;

					if ((*i)->Header.PointerToRawData != 0) {
						assert(OS.tell() == (*i)->Header.PointerToRawData &&
							"Section::PointerToRawData is insane!");

						Asm.WriteSectionData(j, Layout);
					}

					if ((*i)->Relocations.size() > 0) {
						assert(OS.tell() == (*i)->Header.PointerToRelocations &&
							"Section::PointerToRelocations is insane!");

						for (relocations::const_iterator k = (*i)->Relocations.begin(),
							ke = (*i)->Relocations.end();
							k != ke; k++) {
								WriteRelocation(k->Data);
						}
						COFF::relocation r;
						r.SymbolTableIndex = -1;
						r.Type = -1;
						r.VirtualAddress = -1;
						WriteRelocation(r);
					} else
						assert((*i)->Header.PointerToRelocations == 0 &&
						"Section::PointerToRelocations is insane!");
			}
		}

		assert(OS.tell() == Header.PointerToSymbolTable &&
			"Header::PointerToSymbolTable is insane!");

		for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
			if ((*i)->Index != -1)
				WriteSymbol(*i);

		OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
}

//------------------------------------------------------------------------------
// WinCOFFObjectWriter factory function

namespace llvm {
	MCObjectWriter *createWinCOFFObjectWriter(raw_ostream &OS, bool is64Bit) {
		return new WinCOFFObjectWriter(OS, is64Bit);
	}
}
